Implement decoding Opera directories.

DiscImageChef.Filesystems/Opera/Dir.cs

@@ -1,11 +1,57 @@
 using System;
 using System.Collections.Generic;
 using DiscImageChef.CommonTypes.Structs;
+using DiscImageChef.Helpers;
 
 namespace DiscImageChef.Filesystems
 {
     public partial class OperaFS
     {
         public Errno ReadDir(string path, out List<string> contents) => throw new NotImplementedException();
+
+        Dictionary<string, DirectoryEntryWithPointers> DecodeDirectory(int firstBlock)
+        {
+            Dictionary<string, DirectoryEntryWithPointers> entries =
+                new Dictionary<string, DirectoryEntryWithPointers>();
+
+            int nextBlock = firstBlock;
+
+            do
+            {
+                byte[] data =
+                    image.ReadSectors((ulong)(nextBlock * volumeBlockSizeRatio), volumeBlockSizeRatio);
+                DirectoryHeader header = Marshal.ByteArrayToStructureBigEndian<DirectoryHeader>(data);
+                nextBlock = header.next_block;
+
+                int off = (int)header.first_used;
+
+                DirectoryEntry entry = new DirectoryEntry();
+
+                while(off + DirectoryEntrySize < data.Length)
+                {
+                    entry = Marshal.ByteArrayToStructureBigEndian<DirectoryEntry>(data, off, DirectoryEntrySize);
+                    string name = StringHandlers.CToString(entry.name, Encoding);
+
+                    DirectoryEntryWithPointers entryWithPointers =
+                        new DirectoryEntryWithPointers {entry = entry, pointers = new uint[entry.last_copy + 1]};
+
+                    for(int i = 0; i <= entry.last_copy; i++)
+                        entryWithPointers.pointers[i] =
+                            BigEndianBitConverter.ToUInt32(data, off + DirectoryEntrySize + i * 4);
+
+                    entries.Add(name, entryWithPointers);
+
+                    if((entry.flags & (uint)FileFlags.LastEntry)        != 0 ||
+                       (entry.flags & (uint)FileFlags.LastEntryInBlock) != 0) break;
+
+                    off += (int)(DirectoryEntrySize + (entry.last_copy + 1) * 4);
+                }
+
+                if((entry.flags & (uint)FileFlags.LastEntry) != 0) break;
+            }
+            while(nextBlock != -1);
+
+            return entries;
+        }
     }
 }